What are Triplex Pumps?

Triplex pumps are a type of reciprocating positive displacement pump used to move both thin liquids (such as water) and viscous fluids (such as oil).  The pump uses a triple mechanism, usually consisting of three pistons or plungers operating in cylinders that are driven by a single power source.

How do they work?

A single piston pump or plunger pump can be very effective for moving fluids, but the reciprocating motion of the pistons or plungers creates significant pulsations in the discharge pressure, as well as subjecting the driving mechanism of the pump to severe cyclical loads which can cause premature failure of bearings and other mechanical components. However, when more than one piston or plunger are used, it becomes possible to make the flow much smoother, reduce the amount of pressure pulsations, reduce the fatigue loading on the mechanical components of the pump, and the achievable pressure and flow of the pump is also enhanced.

Typically a triplex pump is driven by an A.C. motor, which then has a crank-shaft and connecting rod assembly to convert the rotation of the motor shaft to the reciprocating motion of the pistons or plungers, in much the same way as an internal combustion engine works. Note that there are some piston and plunger pumps with more than three cylinders (quintiplex pumps with five cylinders are common in oil production pumps). The pump typically has a set of check valves for each cylinder, one at the inlet and one at the outlet, which is common for all reciprocating positive displacement pumps.

Where are used?

Small triplex pumps with plungers are commonly used as high pressure wash pumps, sometimes called power washers. These can be used on farms, car washes, and commercial and industrial wash down stations. Very small versions are also used as power washers for home use. Larger versions, both piston and plunger type, are mainly used in applications related to oil drilling and oil well service. All types can be very effective in handling many different kinds of heavy, viscous, and corrosive fluids, including abrasives, slurries, and liquids that contain large amounts of solids.